Formula One champion Lewis Hamilton crashed into the tyre wall but still stayed top of the timesheets after a rain-lashed Canadian Grand Prix practice.
The Mercedes driver put Monaco disappointment behind him to set the pace in a dry morning session before the heavens opened in the afternoon and rendered the Circuit Gilles Villeneuve undriveable.
Hamilton was caught out in the deluge after going out on intermediate tyres, a mere passenger as he braked into the hairpin turn 10 with the car carrying straight on into the barriers at reduced speed.
The red flags came out with about 40 minutes remaining, 10 minutes after the rain first started falling.
"I think he just aquaplaned. The front wing is gone but hopefully no more," said Mercedes motorsport head Toto Wolff after watching the retrieved Mercedes swing back into the recovery tractor as it was pulled clear.
If the times meant little, Hamilton still needed the morale boost after a pitstop blunder cost him a surefire win in Monaco 12 days ago and handed victory to team mate Nico Rosberg instead.
His fastest lap in the morning of one minute 16.212 seconds was 0.415 quicker than Rosberg's fastest effort, and he improved that in the afternoon to 1:15.988 despite crunching over the kerbs.
Mercedes were again dominant at a track whose long straights reward engine performance but put a heavy burden on brakes.
Hamilton, a three-times Canadian GP winner who leads Rosberg by 10 points after six races, had a late spin at the hairpin before lunch but without consequence.
1. Lewis Hamilton (ENG/MER) 1min 15.988sec
2. Sebastian Vettel (GER/FER) +0.316
3. Kimi Raikkonen (FIN/FER) 0.322
4. Nico Rosberg (GER/MER) 0.452
5. Pastor Maldonado (VEN/LOT) 0.612
6. Valtteri Bottas (FIN/WIL) 0.861
7. Romain Grosjean (FRA/LOT) 0.876
8. Felipe Massa (BRA/WIL) 1.053
9. Daniil Kvyat (RUS/RBR) 1.104
10. Daniel Ricciardo (AUS/RBR) 1.123
11. Nico Hulkenberg (GER/FOR) 1.132
12. Marcus Ericsson (SWE/SAU) 1.273
13. Carlos Sainz Jr (ESP/TOR) 1.330
14. Sergio Perez (MEX/FOR) 1.379
15. Fernando Alonso (ESP/MLA) 1.639
16. Max Verstappen (NED/TOR) 1.669
17. Felipe Nasr (BRA/SAU) 1.763
18. Jenson Button (ENG/MLA) 2.147
19. Roberto Merhi (ESP/MAR) 3.543
20. Will Stevens (ENG/MAR) 3.746